The Background of Allegory: Langland and Dante.
Dante makes a person representative of some human aspect, a symbol or embodiment of a pattern of behavior; WL personifies a human aspect and places that allegorical representation in a more or less real setting. Dante seeks to show “the historical representative of a quality in an eternal condition”; WL wants to show the eternal quality realistically in an historical, representative world. Hence there is no sense of time change between dreams in PPl, while in the Commedia vision and the world are kept separate. PPl defines the allegorical figure in its setting and context, and our understanding of a character depends on our accumulating experiences of the figure, e.g., Piers and Conscience.